How to correct this incredible color cast

[bestremera]

This is a Photomatix exposure fusion (not HDR) composite of 3 exposures. I know I was going to get a crazy color cast so I put that white card on the floor hoping that clicking on it with levels/curves white dropper would fix the color. It didn't. It blew out all the highlights and a strange color cast remained. The walls are actually a neutral, almost off-white color. There's almost no light hitting them. They are only 'lit' by virtue of a long exposure.
I know the next thing I'll do is try a gray card instead and of course I can add real lighting to really light up the place but I want to know how to use Photoshop CS6 or LR3 (but probably PS) to work with an extreme color cast problem.
Please help.
Thanks,

[Tony W]

The walls and ceiling are also hit by the reflections of surrounding objects contributing to colour casts.

You could try for a global correction first by using curves and setting the mode to color or saturation. Then add local correction as required.

Few examples to show the effect of sampling different areas using different layer modes

[redcrown]

You use the Levels/Curves GRAY eyedropper to change white balance, not the white.

The white eyedropper says "make this the brightess area (RGB 255)".

[bestremera]

Thanks for the info. The curvescolormode.jpg is interesting. Many of the colors are normalized although there's some crazy color splashes going on. This is very helpful and I'll try the same thing to see how I come out.
Thanks again,

[Tony W]

Originally Posted by redcrown

You use the Levels/Curves GRAY eyedropper to change white balance, not the white.

The white eyedropper says "make this the brightess area (RGB 255)".

And if you do that for this image you end up with an ugly blue cast overall when you sample the white card.

The white eyedropper does say make RGB 255 when in normal mode as it is adjusting color and luminosity. However when you set to colour luminosity of the image is not affected

The image could also be corrected in camera raw for white balance using the card as a ref. point. This may yield a better result - see attachment

[bestremera]

Thanks guys. I've got a lot to work with and I've never gotten this far with this image before.
Thanks for the help.

[Cupcake]

I used color replace.
Reduced the saturation after clicking on it

[bestremera]

Here's the last thing I did, before seeing cupcake's color replace idea that I'm going to try right away.

Reshot today with a gray card instead. clicking on it in LR was way better. Then went in and Desaturated some remaining yellow/orange cast and also desaturated the blues.
Then, I made a took one of the really low outside exposures, made sure the WB was set to daylight, layed in on top of the corrected version, masked it and painted back in the corrected images, leaving the window exposures alone. Also made sure that the trees from outside reflected on the coffee table and TV screen.
Lastly, I did some dodging with the brush set to 'overlay', a trick a photoretoucher showed me.
I think the final is pretty satifsying.

Thanks for all the help, Bob

[mistermonday]

Bob, your last effort is getting closer but it looks like you have a magenta cast over midtones and shadows. You may have better luch with a Channel Mixer adjustment layer tweaking the blue channel.
All that being said, I can say that my experiences with Photomatix have been color shifts. This image should lend itself very well to Oloneo's PhotoEngine. It's the most color accurate of any HDR app out there. Moreover there is a panel in the tonemapper that has a set of graphs that function just like the HSL tab in Caamera RAW or LR that allow you to adjust the hue, sat, and luminance independently in each color range of the spectrum. If you do not want to try the trial version and would like to post your RAW files somewhere, I would be happy to run them through for a comparison.
Cheers, Murray

[bestremera]

Hey mister Monday,
For the final magenta cast, changed the mode to CMYK, put a curves layer on and reduced the magenta. For one last resistant area on the ceiling, I did a replace color and selected an area of the ceiling that had a neutral color and painted it on.
Thanks for the help. Also that Oloneo PhotoEngine sounds promising.
Bob